Complex surface carbohydrates act as receptors; however, whether they do so in growth regulation has received no direct confirmation. It is the object of this research project to study surface glycopeptide alterations and to attempt to correlate these changes with the growth of a cell. Surface glycopeptides from a variety of cells will be labeled with radioactive carbohydrate precursors and after brief proteolysis, the glycopeptides will be separated into neutral and acidic species. Using glycosidases of known specificity, we will characterize the core alterations oligosaccharide moieties and relate the alterations to the growth properties of cells to be studied. We also plan to directly test the effect of related, purified surface glycopeptides on the growth of cells and to study their modification during various stages of cell cycle as well as during their various growth phases. The synthesis and turnover of protease release glycopeptides will be investigated. These studies are important if an assessment of the relative amount of a particular labeled species (glycopeptide) in different growth states is to be made. We will also use Vesicular Stomatitis Virus (VSV) and Sindbis as probes to study whether or not changes in carbohydrate composition and/or sequence require changes in the primary sequence of the protein. These viruses offer the advantages of having only one (VSV) or two (Sindbis) glycoproteins in their coat. These glycoproteins can be easily isolated and purified and consequently one can analyze fairly homogeneous species.